Manufacture of wrought iron



Patented 38.11.25, 1944 7 2,339,821 MANUFACTURE OF wit o uon'r} moN Edward is. Story, Bethel- Township; Alle heny County, Pa.,' assignor to A. M. Byers Company, Pittsburgh, Pa., a corporation of Pennsylvania No Drawing. Application May 15, 1942,

v Serial No. 443,14l

5 Claims. c1. 75-47) This invention relates to manufacture of wrought iron by the Aston process. It relates more particularly to the discoVeryI'Otcertain I I factors contributing to the production by the Aston proces of wrought ironof superior quality.

In the manufacture of wrought ironby the Aston process molten refined ferrous material is admixed with molten iron oxide silicate slag to form asponge ball in .-the presence of an excess of slag, the ball is separated from the excess slag which does not become incorporatedin the ball and the thus separated ball is compressed, to expel a portion of the slag contained therein whereby to form a wrought iron mass or bloom 1 .which may be rolled or otherwise worked., Pref- 'erably the molten. refinedferrous "material is poured into a bath" of molten slag, the ferrous material passing downwardly through the slag bath and being disintegrated during such passage and forming at the bottom of the receptacle in which the slag is contained a Welded spongy mass of metalwith slag inclusions com- "monly referred to as a ball." Y

For production of wrought iron of high quality the slagkincluded in the ball should be squeezed out to the greatest possible extent. ,The compression or squeezing of the ball may be accomplished in any suitable apparatus, ,a hydraulic press being preferred. It is important that the ball as delivered to the press be at as high a temperature as possible consistent with good practice in other respects as the higher the temperature of the ball as delivered to thepress the more included slag will be squeezed out. There is a practical limit to the squeezing or compressing pressure which can be applied to the ball and the results which can be obtained cular shape in transverse cross section and its transverse dimension is roughly equal to its thickness. Depending upon the shape of the receptacle the ball may have more or lessfiat side faces and a more or less fiat bottom, and'in such case it is desirable that its shapeapproa'ch that of a cube with outwardly curved faces and curved edges and corners.

The primaryconsideration with respect to the shape of the ball is that its surface should be as limited as practicable relativelyto its volume. A sphere .has the least surface per unit of volume of any solid. The smaller theexposed surface. otthe ball relativelyto itsvolume the less will be the heat loss between the time the ball is separated from the excess slag and the time it is squeezed in the press. Also the smaller the exposed surface of the ball relatively'to its volume the less will be the oxidation of themetal in the ball after its separation from the excess slag. Consequently it is important to definitely limit the respective dimensions of the ball so that its shape will"as nearlyas prac-- ticable approximate the desired shape as above explained.

I have found that for best pram .the depth of theball formed, in the slag receptacle. should closely approach or approximate the depth of the slag before any of the molten refined ferrous A material is poured, in. However, thelsla'g depth is also directlyrelated to the temperature of the moltenrefined ferrous material as the hotter the molten refined ferrous material the deeper 9 must be the slag (for a given temperature "of the slag) in order to insure proper disintegra- I tion and welding of the metal in forming the by increase of pressure for a ball of given temperature and it is not practicable to endeavor to make up for relatively low temperature of the ball by the application of relatively high pressure in the press to thereby attempt to squeeze out as much slag as would normally be squeezed out of a ball of desirably high temperature.

' I have found that the shape of the ball formed,

in the slag receptacle has a direct bearing upon the results obtained in the press. The ball'should approach as nearly as practicable the shape of a sphere for theoretically best results, although due to the conditions obtaining in making of the ball it is not possible to obtain this maximumtheoretical desideratum. Superior results are obtainedif the greatest transverse dimen sion of the ball is not greater than twice its thickness. Preferably the ball approaches "cirg as the entrained slag would not have sufficient ball. I have found'that to avoid increasing the slag depth above that which is desired for formation of a ball of the preferred'shape the temperature of the molten refined ferrous material as poured into the slag should be between about 2800" F. and about 2900 F.

Another and van important factor, however, is the temperature of the slag itself. before the molten refinedferrous material is poured in. If the slag is relatively hot it will have to be relatively deep to accomplish the desired results in ball formation just as the slag wculdhave to be relatively deep if the metal were relatively 11013. On the other hand, if the slag is relatively cold the result may be a failure to properly disintegrate the metal and cause it to weld into the ball fluidity. I have found that the temperature of the slag should be between about 2475 F. and

about 2550" F. in order to form a ball of the desired shape when using molten refined ferrous material whose temperature as poured into the slag is between about 2800 F. and about 2900 I".

When the temperature of the slag in the bath 5 is between about 2475 F. and about 2550" F. and the temperature of the molten refined ferrous material as poured into theslag is betweenabout. 2800 F.- and about 2900 F. and the ballformed is desirable to keep all of the factors simultaneously within the ranges stated.

. Another advantage in making a ball whosegreatest transverse dimension is not greater than twice its thickness is that such a ball may most efi q ently be compressed or squeezed inthe press. If a decidedly elongated ball or sausage-like wrough iron sponge mass isformed, it is not only subject to excessive cooling and oxidation but is not susceptible of most efficient formation into a bloom or working mass in'the press. Formerly when the rotary squeezer was used for squeezing out the excess slag it was thought by some to be desirable to form a substantially longated ball,

but such ball had disadvantages in respect of heat dissipation and oxidation and with the hydraulic press which is now preferred the ballis desirably I of roughly spherical or cubical shape.

Since the volume of slag employed is several times the volume of metal (ordinarily between 8 a and 20 timeshthe temperature of the slag is perhaps the most important factor in bringing about the desired re'sultsin the press and the production of wrought iron of superior quality.

' I have found that if the-temperature of the slag H before pouring in the molten refined ferrous material is maintained between about '24'l5 F. and about 2550" F. highly satisfactbryresults are ob- I tained. I This may at timesbe'true even though kept within the limits herein defined uniform production of wrought iron of the highest quality is insured.

While I have described a present preferred method of practicing the invention it is to be distinctly understood that the invention is not limited thereto but may be otherwise variously practicedwithin the scope of the following claims.

I claim:

10 1. In the manufacture of wrought iron by the Aston process, admixing molten refined ferrous material and molten slag having a temperature between about 2475" F. and about 2550 F. to form a vwrough iron sponge ball, expelling a pertion of the, slag fromthe ball and working the wrought iron thus produced.

2. In the manufacture of wrought iron by the Aston process, admixing molten refined ferrous material and molten slag having a temperature between about 2475 F. and about 2550 F. to

form a wrought iron sponge ball whose greatest transverse dimension is not greater'than twice its thickness, expelling a portion of the slag from the ball and working the wrought iron thus pro- 2 duced.

3. In the manufacture of wrought iron by the Aston process, admixing molten refined ferrous material having a "temperature between about 2800 F. an dabout 2900 F. and molten slag havingatemperaturebetween about 2475F. and

about 2550 F. to form a wrought iron sponge ball, expelling a portion of the slag from the ball and working the wrought iron thus produced.

-' 4'. In the manufacture ofwrought iron by the Aston process, admixing molten reflnedferrous material having a temperature between-about 2800 F. and about 2900" F. and molten slag to form a wrought iron sponge ball whose greatest transverse'dimension is not greater than twice 40 its thickness, expelling a portion of the slag from I the ball and working the wrought iron thus produced.

5. In the manufacture of wrought ironby the Aston process, admixing molten refined ferrous u material having 'a temperaturebetween about 2800 and about 2900 F. and molten slag having a temperature betwen about 2475 F. and about 2550 F. to form a wrought ironsponge ball whose greatest transverse dimension is not the temperature of the metal may be somewhat greater than twice its thickness, expelling a. poroutside the rangeabove referred to and even though the shape of the ball may diifer somewhat from the desired shape. However, as above indicated, when all of the factors mentioned are tion of the slag from the ball and working the wrought iron thus produced.

EDWARD B. STORY. 

